A 'natural' solution for transportation

Researchers at Argonne have begun to investigate adding one more contender to the list of possible energy sources for light-duty cars and trucks: compressed natural gas (CNG). Credit: Mercedes Benz.

As the United States transitions away from a primarily petroleum-based transportation industry, a number of different alternative fuel sourcesethanol, biodiesel, electricity and hydrogenhave each shown their own promise. Hoping to expand the pool even further, researchers at the U.S. Department of Energy's Argonne National Laboratory have begun to investigate adding one more contender to the list of possible energy sources for light-duty cars and trucks: compressed natural gas (CNG).

Compressed natural gas is composed primarily of methane, which when compressed occupies less than one percent of the volume it occupies at standard pressure. CNG is typically stored in cylindrical tanks that would be carried onboard the vehicles it fuels.

Because the domestic production of natural gas has increased dramatically over the past ten years, making a large number of the cars and light trucks currently on the road CNG-compatible would help to improve U.S. energy security. "As a country, we don't lack for natural gas deposits," said Argonne mechanical engineer Thomas Wallner. "There are fewer obvious challenges with direct supply than with most other fuels."

Natural gas currently comes primarily from deep underground rock structures, including shale. Recent improvements with hydraulic fracturing, or "fracking," a controversial process that some critics claim can hurt the environment, have made it economical for natural gas companies to extract a greater supply of natural gas from unconventional sources.

Like gasoline, both the production and combustion of CNG release greenhouse gases into the atmosphere. To be able to make an accurate comparison to gasoline, scientists and engineers will need to look at each stage of the fuel's production and use, said Argonne environmental scientist Andrew Burnham.

Unlike gasoline, however, CNG markets are relatively insulated from geopolitical shocks, said Wallner. "The price of CNG has been and will probably continue to be both cheaper and more stable over the long term than gasoline," he said.

CNG currently costs the equivalent of about $2 per gallon, roughly half that of current gasoline prices, according to Wallner.

In order for CNG to take hold, many more stations will need to offer it as an option, and the infrastructure for delivering and distributing the fuel around the country will have to be built up. There are currently fewer than 1,000 publically available CNG refueling stations in the United States, in comparison to nearly 200,000 gas stations.

Argonne already has the capability to help automotive industry leaders test and analyze CNG vehicles. In particular, Argonne's Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model gives experts the ability to examine the greenhouse gas emissions of various fuels from "well-to-wheels," involving each stage of production, distribution and combustion. "We have years of expertise working with industry to develop alternative-fuel vehicles as well as the tools necessary for the public to understand the impact of these vehicles on the environment," said Argonne mechanical engineer Michael Duoba.

Although CNG vehicles emit fewer greenhouse gases than conventional automobiles as fuel is combusted, "upstream" challenges in production and distribution of CNGparticularly methane leakage -- make it somewhat less attractive when it comes to preventing climate change. "There are a lot of points in the life-cycle of the fuel where we still need better data," Burnham said. "There are technological opportunities for us to capture the leaked natural gas and reduce greenhouse gas impacts."

For heavy-duty applications, like city buses, CNG might have the potential to cut down emissions of particulate matter and nitrogen oxides, helping municipalities to meet more stringent EPA standards enacted in the past few years, according to Burnham.

In Wallner's view, CNG vehicleslike plug-ins and diesel-powered automobileswill serve the transportation needs of some, not all. "It's important to see each of these technologies as a part of the solution but not the entire solution," he said. "The more we invest in their development, the closer we'll come to a portfolio that makes sense both economically and environmentally."

Related Stories

A pioneering program by one of the world's largest cities to switch its vehicle fleet to clean fuel has not significantly improved harmful vehicle emissions in more than 5,000 vehicles  and worsened some vehicles' climate ...

Few drivers know exactly which well in which country their gasoline comes from, and from an environmental standpoint, it may not matter. Burning petroleum from the United States, Canada, Russia or Iran would each release ...

A transition to hydrogen vehicles could greatly reduce U.S. oil dependence and carbon dioxide emissions, says a new congressionally mandated report from the National Research Council, but making hydrogen vehicles competitive ...

If you are looking for an environmentally friendly automobile, think about getting a hybrid car or one running on natural-gas. In terms of CO2 emissions both perform significantly better than gasoline or diesel fuelled vehicles. ...

Studying data from Twitter, University of Illinois researchers found that less people tweet per capita from larger cities than in smaller ones, indicating an unexpected trend that has implications in understanding urban pace ...

Unpacking groceries is a straightforward albeit tedious task: You reach into a bag, feel around for an item, and pull it out. A quick glance will tell you what the item is and where it should be stored.

A new online game puts players in the shoes of an aspiring propagandist to give the public a taste of the techniques and motivations behind the spread of disinformation—potentially "inoculating" them against the influence ...

It's a safe bet that some of the websites and apps you use collect and subsequently sell your personal data. But how can you know which ones? An EPFL researcher has led the development of a program that can answer that question ...

Methane happens to be the easiest biofuel to produce. You toss biomatter and water in a bucket, introduce methanogenic bacteria, and they convert 99% of the stuff they can eat into methane in the absence of oxygen.

CNG is basically methane, so once the fossil supplies run out, we can simply make more.

And CNG engines can easily run on propane or other gaseous fuels. The lack of infrastructure is not a problem as long as the local fuel station has a propane tank, or has standard propane cylinders that they send for refills. You can bridge the gap with propane until there's enough CNG vehicles around to warrant a dedicated tank and pump.

One pound of propane equals roughly 0.17 gallons of gasoline, so a standard 20 pound propane cylinder contains the equivalent of 3.4 gallons of fuel.

If your car does 40 miles to the gallon, that's 137 miles you can drive, and when you run out you just pull up and exchange your cylinder to a full one.

If the engine in your car was actually a SOFC (a fuel cell), it would turn over 50% of the fuel into electricity. Assuming 250 Wh per mile and 50% overall efficiency, you'd go about 230 miles on a 20 pound cylinder.

So, it's not a problem at all if you can't find a CNG pump. Most fuel stations have propane refills, and if you keep visiting the same station for a fill-up, it becomes more economical for them to get a CNG pump for you.

The US and 50 state govts are going to have to shift from a gasoline use tax to something else or the states and feds will oppose alternate fueled vehicles.The only reasonable alternate will be some type of toll system. GPS and cellular technologies will enable methods for documenting and recording the toll charges. This would also support traffic management changing toll rates as a function of the time of day.

ethanol: 1/2 the btu/lbs of petroleum. costs more in energy to make and distribute than is recovered in its burning

Electricity is made from coal. Coal is good. Coal is great. Coal will be our savior. But it is more efficient to turn the coal into synthetic gasoline and burn it as gas, rather than burning coal into electricity, then storing that electricity in batteries.

Biodiesel is good as long as it is made from waste products. But it too, costs more in energy to produce than it releases in combustion.

Hydrogen is not an energy source it is a form of energy storage. There ARE NO HYDROGEN MINES. It also costs more energy to produce than it releases in combustion.

Electricity is made from coal. Coal is good. Coal is great. Coal will be our savior. But it is more efficient to turn the coal into synthetic gasoline and burn it as gas, rather than burning coal into electricity, then storing that electricity in batteries.

Not really. The process of turning coal into gasoline requires a lot of water, and it runs at 50% efficiency at best because you also need to produce hydrogen on the side. Gasoline, after all, is a hydrocarbon.

50% left after production, 25% left after the engine, leaves you with just 12% of what you started with.

Electric cars on the other hand, 37% at the turbine, 75% at the end of the grid and through the battery, leaves you with 28% of your energy remaining.

Of course it does. That's thermodynamic second law. Currently water electrolysis is from 50 to 70 efficient. If electricity is made from renewable energies, then it is not a big problem. It may be a nice way to store energy. Unfortunately, hydrogen needs to be stored at very high pressure (up to 700 bar) so it is quite unpractical. Also, the lack of infrastructure is a showstopper. There is no silver bullet.

Methane happens to be the easiest biofuel to produce. You toss biomatter and water in a bucket, introduce methanogenic bacteria, and they convert 99% of the stuff they can eat into methane in the absence of oxygen.

The article talks about gas foound in the ground ('shale', 'deposits', ...) and released via fracking. Doesn't sound like environmentally friendly/sustainable solutions are part of the idea.

The article talks about gas foound in the ground ('shale', 'deposits', ...) and released via fracking. Doesn't sound like environmentally friendly/sustainable solutions are part of the idea.

It can also be made from organic waste. Overall, CNG is certainly the most interesting carbon-based fuel and the cleanest. I doubt the electric car industry will grow as fast as we'd want. Maybe CNG can participate.

Burning stuff in a carnot cycle for mobility just seems so last millennium.

What is more efficient, robust and ready for prime time?

Batteries are just too bulky and expensive for transportation. We will have to wait a few years before we can ditch our ICE. Plus they are becoming much more efficient. Direct injection just started. Now people play with EGR, valve timing, injection pressure, multi-shot injection, injection timing, throttle-by-wire, boost pressure. We are starting to optimize all these parameters at the same time.

They're not yet reliably miniaturized to vehicle use, but if you want to make electricity out of methane, they're pretty much the best you can get.

The only thing that can compete in efficiency are complex multi-stage combined cycle powerplants that basically run jet engines to turn generators and then steam turbines with the exhaust heat of the jet engines.

The IAP Short Course (7 days) on Cold Fusion and Lattice Assisted Nuclear Reactions at Massachusetts Institute of Technology MIT has meticulously developed the salient point that skeptics of cold fusion were wrong, and that scientific theories do exist for understanding the difficult to achieve reactions. http://coldfusion...it-again This solution will indeed make all "natural" solutions pretty uncompetitive. Wouldn't be cheaper and more considerate environmentally to invest into cold fusion research directly, rather than into methods of harvesting of methane from rocks? These methods aren't cheap and environmentally friendly at all. The methane is expelled from rock with hot steam and detergents, which contaminate the sources of underground water. http://news.natio...n-water/

That really depends on what kind of countries and with what kind of infrastructure present you're looking at.In most of Europe electric vehicles are ready for prime time because distances are shorter and the ability to put up a recharge-station infrastructure in minimal time is there.

In the US...well...oil is probably the thing that will have to be used for the foreseeable future.

I have heard tourists to the USA say that they plan to drive around the US visiting the most popular tourist spots. The first day they plan to visit the Statue of Liberty, the second day Chicago, the third day the Grand Canyon, ...If anyone plans to drive across the country, or even a 2-3 day drive, if one has to map out fuel stop because of a specialty fueled vehicle, most people would use a vehicle the can be fueled at any fuel station along the route.I like the idea of driving a car onto a freight train and letting it do the driving while I hang out in a passenger car. But there are rules against that.

In most of Europe electric vehicles are ready for prime time because distances are shorter and the ability to put up a recharge-station infrastructure in minimal time is there.

In the US...well...oil is probably the thing that will have to be used for the foreseeable future.

Technically, Europe is bigger than the US. Go from Portugal to Lapland, and that's something like 5000 miles for you. The difference is that there isn't a culture of driving from coast to coast just to meet your grandparents, because they're likely to live in the same state as you.

The difference is that there isn't a culture of driving from coast to coast just to meet your grandparents, because they're likely to live in the same state as you.

One can travel across all 50 states and still speak the same language and use the same money and not need a passport.Driving 5-6 days across the country is not as common as flying. 5-6 days vs 6-7 hours flying?

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.